Boat Trailer Maintenance

A third of the 100,000 plus boats for sale on this website are listed with trailers. That’s no surprise because according to BoatUS, nearly 7 million Americans own a boat with a trailer. Most likely, you’ve seen some of those boaters pulled over on the side of the road with trailer problems–wheels off, axles broken, people in a state of frustration and panic as their prized boat hangs in the balance over a broken down trailer. If you are like me, you’re first reaction is, “Oh, that poor slob, I’m glad that’s not me.”


Most boats under 25 feet are trailerable.

Truth be told, not enough of us pay enough attention to the condition of our boat trailers. Following a few simple tips on maintenance can reduce the possibility of that breakdown on the side of the road.

Top Five Causes of Boat Trailer Service Calls

The top five reasons for service calls to the BoatU.S. boat trailer roadside assistance program are:

  • 44% – Flat Tires
  • 20% – Wheel Bearing Failures
  • 14% – Axle Problems
  • 9% – Suspension Problems
  • 5% – Tongue/Coupling Trouble
bearing buddy

Bearing Buddys are spring loaded hubs that constantly force grease into the bearing

Trailer or ST tires are different from car tires—they’re usually of a bias ply design, which provides higher load capacity and stiffer sidewalls compared to the more flexible radial tire design found on most passenger cars.

Under inflation is the prime cause of trailer tire problems. An underinflated trailer tire won’t sag like your car’s tires because of its stiff sidewall construction. Tires may look normal, but only a pressure gauge can accurately show proper inflation. You can’t eyeball it! Check your tire pressure with a tire gauge.

Oxidation is often the next culprit for trailer tire failure. Trailer tires need to be replaced every 3–5 years of use, even though they usually appear to have plenty of tread left. Trailer tires often sit in one spot for weeks, if not months, subject to UV radiation. Is it any wonder that the deteriorated sidewalls blow out under pressure? Check for dry rot and crazing on the sidewalls.

Wheel bearing problems
Boat trailers are regularly immersed in water–often in corrosive salt water. Even fresh water will cause the wheel bearings to rust if not properly packed with lubricant.  Very few owners check the lubrication of the hubs and bearings as often as they should (like before every road trip). Even if they do, they don’t always use the right lubricant. Fill the hubs completely with a multipurpose No. 2 grade lubricant.

One solution is to use a spring-loaded hub, such as Bearing Buddy, that constantly forces fresh lubricant into the wheel bearing. Some models of Bearing Buddy even have a visual exterior reference to show you at a glance if there is enough lubricant in the hub. I’ve personally installed these on my own trailer and recommend them.

Even trailers not immersed in water are subject to bearing corrosion. Condensation will be sucked into hot hubs as they cool if they are not completely filled with lubricant, causing rust and pitting. The only solution is to be vigilant about lubricating your wheel bearings.

trailer rust

Axle and suspension problems may be due to corrosion but are just as likely to be from overloading

Axle, suspension, and tongue/coupling problems
Assuming your trailer has passed a visual inspection for rust and corrosion, the most likely cause of axle, suspension, or coupling problems is overloading. Another common cause is not following safe towing techniques.

Inspecting Your Trailer
Have you ever noticed that trailers stranded on the side of the road tend to have more than one problem? For instance, trailers with inoperative lights are also the same ones that have not been inspected or maintained for other, more serious problems. Before you trailer your boat, always perform a walk-around inspection.

  • Check your tire pressure with a tire gauge.
  • Check for dry rot and crazing on the sidewalls.
  • Grease wheel bearings with No. 2 grade lubricant before every trip (Don’t mix grease types).
  • Check your lights.
  • Visually check for rust and corrosion

Prudent trailer owners should carry a spare tire, a grease gun, and tire gauge. When not in use cover trailer tires with covers like you see on RV’s. If you follow these trailer maintenance tips, you’ll greatly reduce the odds of being that “poor slob” stuck on the side of the road.